A 19-year-old college student presents with 3 weeks of pruritic rash on the scalp and eyebrows. He reports intermittent “dandruff” for years that has recently worsened during exam stress. He has no fever or systemic symptoms. Physical exam shows greasy, erythematous plaques along the scalp margin and within the eyebrows with overlying white-yellow flaky material that can be brushed off. Which of the following best describes the type of skin lesion represented by the flaky material overlying these plaques?